Ferrule for snowmobile track

ABSTRACT

An improved, reinforcing ferrule for the crossbars of an endless flexible track or belt used for driving snowmobiles or like apparatus. The ends of the ferrule are flared at the longitudinal ends thereof in the horizontal plane of the track.

United States Patent 111 Nichols 10/1960 Backhaus.....

[5 FERRULE FOR SNOWMOBILE TRACK 3,722,963 3 1973 2,957,? 1 [75]Inventor: George Ottawa 2 704 932 3 1955 [73] Assignee: The StandardProducts Company,

Cleveland Ohio Primary Examiner-Richard J. Johnson [22] Filed; O t, 19,1972 Att0rney-James H. Tilberry et a1.

[21] Appl. No.: 299,047

ABSTRACT An improved, reinforcing ferrule for the Crossbars of anendless flexible track or belt used for driving snow- 847 325 my 05% 3 a28 W 3 MHO Wmh m mwe L hf C d s UmF 1]] 2 8 555 [[l.

[56] References Cited UNITED STATES PATENTS 11/1969 McNeil 13 Claims, 4Drawing Figures FERRULE FOR SNOWMOBILE TRACK This invention relates tothe art of endless drive belts of flexible tracks and more particularlyto an improved ferrule arrangement for the crossbars thereof.

The invention is particularly applicable to a ferrule arrangement forthe endless track of a motor-driven snowmobile and will be describedwith particular reference thereto; however, it is to be understood thatthe principles of the invention have broader applications and may beemployed in other instances with the various types of endless belts ortracks.

The track construction employed in snowmobiles and the like generallycomprises two or more endless belts of molded rubber having a pluralityof spaced, transversely-extending crossbars embedded therein to maintainthe endless belts in a desired spaced parallel relationship. A ferruleor spacer or bushing generally is applied to each crossbar betweenadjacent edges of the endless belts. The drive means for the trackusually comprises a mechanically driven sprocket which engages theferrules to effect movement of the track. This type of drive arrangementis deemed conventional so that further elaboration thereon is notrequired. U. S. Pat. No. 3,477,766 issued Nov. 11, 1969 to G. I. McNeil,however, illustrates the above described construction.

Tracks thus typically constructed have heretofore experiencedsubstantial crossbar failures during ordinary services. These failuresgenerally require replacement of the complete track at considerableexpense to the owner of the vehicle. It has been found that thecrossbars have fatigued primarily as a result of high dynamic, singlepoint tooth loadings exerted on the crossbar during driving operationthereof.

In an effort to alleviate the fatigue failures described above,ferrules, or crossbar protective members were developed. Ferrules incurrent use aggravate this condition, however, because a uniformlydistributed sprocket tooth loading is transmitted by the ferrule to thecrossbar as single point end loadings. These single point end loadings,representing stress concentrations, materially decrease the life of thecrossbars.

The present invention comtemplates a new and improved ferrule for use onan endless track overcomes the above referred to problems and others andprovides a ferrule which substantially increases crossbar life and issimple in design and easy to manufacture.

In accordance with the present invention, the ferrule is comprised ofgenerally flat upper and lower surfaces communicating with arcuateforward and rearward surfaces. The forward and rearward surfaces areflared in a horizontal plane at the longitudinal ends thereof generallyparallel to the upper and lower surfaces.

In accordance with another aspect of the present invention, the ferruleincludes a longitudinally extending slit-like area along either itsupper or lower surface to permit a slight deflection of the ferruleunder loading. The slit-like area is preferably V-shaped.

In accordance with still another aspect of the present invention, theupper surface of the ferrule is flat so as to establish a generally flatrelationship between the ferrule and the surfaces of the endless rubberbelts.

It is the principal object of the present invention to provide aflexible track or endless belt which has a greater life expectancy thanthose heretofore in existence.

Another object of the present invention is the provision of means toremove the stress concentration imposed on the crossbars by the ferrulesdun'ng driving operation of the track.

Another object of the present invention is the provision of means toaccurately position the crossbar in the belt molds when molding thetrack.

Still another object of the present invention is the provision of meansto distribute end loadings of the ferrule over portions of the crossbarand to insure uniform loading over the entire crossbar.

A further object of the present invention is the provision of animproved ferrule which is readily adaptable to use with any number ofspecific endless track designs.

The invention may take physical form in certain parts and arrangementsof parts, a preferred embodiment of which will be described in detail inthis specification and illustrated in the accompanying drawings whichform a part hereof and wherein:

FIG. 1 is a perspective view of an endless belt showing the generalarrangement of component parts.

FIG. 2 is a cross-sectional view taken along lines 22 of FIG. 1;

FIG. 3 is a cross-sectional view taken along lines 33 of FIG. 1; and,

FIG. 4 is a plan view of a ferrule formed in accordance with theconcepts of the subject invention.

Referring now to the drawings wherein the showings. are for the purposeof illustrating a preferred embodiment of the invention only and not forpurposes of limiting same, FIG. 1 generally illustrates an endlessflexible track A for use in a snowmobile driven by a conventionalsprocket B. Flexible track A is comprised of at least a pair of endlessrubber belts generally designated 10,12 interconnected by a plurality oftransversely extending crossbars 14 embedded therein. The constructionof track A is deemed to be conventional so that further elaborationthereon is not required. A ferrule fits over each crossbar 14 andextends between endless belts 10,12.

As best shown in FIGS. 1 and 2, belts 10,12 are identical but oppositelydisposed to each other and include generally flat interior surfaces 20and irregular terrain engaging exterior surfaces 22. Flat interiorsurfaces 20 engage a conventional slide or suspension unit on thevehicle itself, which slide is shown in phantom in FIG. 2. Exteriorsurface 22 engages the terrain and includes a plurality of rectangulardepressions 24 disposed therealong. Depressions 24 are defined by innerand outer longitudinally extending ridges 26,28 bisected by transverselyextending ribs 30. Other configurations for depressions 24 may beemployed as desired without affecting the scope and intent of thesubject invention.

Crossbars 14 extend transversely of track A parallel to one another atspaced intervals corresponding to the pitch between consecutive teeth 40of sprocket B. These crossbars may be of any desired material butpreferably are of high carbon or alloyed steel. Each crossbar comprisesan elongated, generally flat member having a width dimension greaterthan the thickness dimension and including an exposed middle portion 42and identical, mounted end portions 44,46. End portions 44,46 areembedded in belts 10,12 respectively and conveniently secured againstmovement.

therein by means of being wrapped in a relatively stiff, canvas-typematerial 48. This structure provides a relatively low section modulus inthe vertical plane by virtue of the smaller thckness dimension whichpermits track A to flex vertically. Also, there is afforded a relativelyhigh section modulus in a horizontal plane tending to reduce flexure ofthe crossbars from sprocket gear teeth loading.

The exposed middle portion 42 is defined as those portions of thecrossbars extending between inner longitudinally extending ridges 26 ofbelts 10,12. As best shown in FIG. 3, each crossbar 14 includesgenerally flat, upper and lower surfaces 50,52 and arcuate forward andrearward surfaces 54,56 respectively which blend into the upper andlower surfaces. In the preferred embodiment of the invention, theforward and rearward surfaces are defined by equal radii R-l tangentialto the upper and lower surfaces, although other arcuate configurationscould also be employed. It should be noted that the above describedconfiguration of crossbars 14 is for all the portions 42,46 and 48.

The elongated ferrules generally designated 16 are each adapted to fitover a crossbar middle portion 42. Although the ferrules may beconstructed from any desired material, hardened or alloyed steel ispreferred. Each ferrule extends between belts 10,12 and includes flaredends 60,62 abutting the longitudinally extending inner edges of theopposing belts. Each ferrule has generally flat upper and lower wallportions 64,66 integral with arcuate forward and rearward wall portions68,70 respectively. In the preferred embodiment of the invention, and asbest shown in FIG. 3, each of these wall portions has interior andexterior surfaces. The interior surfaces of wall portions 68,70 aredimensioned to closely embrace portions 54,56 of crossbar 14 and wallportions 64,66 are dimensioned so that a clearance area is providedbetween the interior surfaces therof and upper and lower surfaces 50,52respectively of the crossbar. With this arrangement and when the ferruleincludes flared ends 60,62, the crossbar may flex in all directionsduring track use without the establishment of any undesirable stresspoints thereon. Such stress points would otherwise be established duringtrack use as flexure of the crossbar in any direction caused it tocontact the ends of the ferrule. The close fitting relationship betweenthe interior surfaces of ferrule wall portions 68,70 and crossbarportions 54,56 acts to retain the ferrule in its proper position duringtrack use. With respect to the exterior surfaces of wall portions 68,70,it should be noted that they may assume any arcuate configuration aslong as proper engaging contact may be made with sprocket teeth 40. Asshown in FIG. 2, the exterior surfaces of wall portions 64,66 are suchthat they are generally coplanar with interior and exterior surfaces20,22 of belts 10,12. Thus, at least the entire interior surface oftrack A is flat so that interference with the snowmobile suspensionslide (phantom in FIG. 2) is avoided.

Extending longitudinally along either of upper or lower wall portions64,66 of the ferrule is a slit. In the preferred embodiment this slit isdesignated by numeral 80 and is disposed to extend through upper portion64. From FIG. 3, it will be seen that the slit is generally V- shaped.The included angle a between the side of the V-shaped slit is preferablywithin Ito although other angles may be employed without departing fromthe scope of the invention. The base or innermost part 82 of slit 80 andpreferrably within the tolerances of 0.00 inches to 0.04 inches,although other suitable openings may be applied and acceptably employed.When assembled ov'er crossbar middle portion 42, ferrule 16 is slightlyexpanded to a prestressed condition to provide further assurance that itwill not rotate around the crossbar when a load from sprocket B isapplied during vehicle operation. Slit also assures that the sprockettooth loading will be uniformly distributed over the middle portion ofthe crossbar.

The longitudinal ends 60,62 of forward and rearward wall portions 68,70are desirably flared outwardly in a generally horizontal plane. Theflaring of ends 60,62 originates from points or lines of flare 90,92 onboth the forward and rearward wall portions 68,70. The lo cation of thepoints or lines of flare are determined by the width of teeth 40 onsprocket B and the tolerance of the track within suspension slide andtrack guide. In the preferred embodiment for a standard arrangement, thepoints of flare 90,92 are located inwardly of end portions 60,62approximately one-quarter inch in a ferrule 14 of approximately 1%inches in length. Generally, flared ends 60,62 originate from lines offlare which are straight although it will be apparent that the lines offlare could take arcuate paths. Thus, and as shown in the preferredembodiment, the lines of flare are comprised of a radius 1 1-2. 7

As thus constructed, ferrules 16 assure a uniform distribution of loadon crossbars 14 inasmuch as flared ends 60,62 prevent end pointloadings. Further, when the flared ends are constructed along arcuatelines of flare, any tendency of the sprocket tooth force to concentrateat the points of flare is eliminated as the force distributes itselfover the arcuate path presented thereby.

Several advantages of the above described construction should beadditionally noted. One such feature which increases the uniformdistribution of load thereon while also avoiding the adverse effects ofstress concentrations is the utilization of the rubber from thetrack-forming process which fills the space between the flares of theferrules and the crossbars. Thus, if point loading was to occur at theflared ends of the ferrules, the loading would be uniformly distributedby the rubber.

An additional feature of the invention resides in the economics of itsconstruction and application to crossbars 14. Ferrules presently in useare solid, one-piece constructions so that it is extremely difficult toflare them. Because the subject new ferrule design includes alongitudinal slit 80, it is relatively easy to flare ends 60,62 alongany desired line or path by a simple press operation. Further, criticalassembly tolerances are eliminated because the ferrules are slightlystressed when applied to the crossbars 14.

Another desirable attribute of the subject new ferrule resides in theuse of the ferrule during manufacture of track A. The track is usuallyformed by injecting rubber or rubber compositions into a mold to formthe elongated belts 10,12 with crossbars 14 in place. Prior to injectingthe rubber, the crossbars must be accurately positioned within the moldin both the horizontal and vertical planes and the crossbar end portionsat least wrapped with canvas material 48. As it is the attitude of theferrules with respect to each other which is critical, it will be seenthat flared ends.60,62 provide readily accessible areas for holdingfixtures. Furthermore, and during molding, the flared ends additionallyassure alignment of the ferrules by receiving rubber material thereinsince, and as noted above, the crossbar middle portions 42 extendpartially into the opposed inner edges of belts 10,12. Thus, in a sense,the crossbars have their middle portions integrally molded with belts10,12 to assure accurate overall construction of the track.

The invention has been described with reference to the preferredembodiment. Obviously, modifications and alterations will occur toothers upon the reading and understanding of this specification. It ismy intention to include all such modifications and alterations insofaras they come within the scope of the appended claims or the equivalentsthereof.

Having thus described my invention, I now claim:

1. In an endless, flexible track comprised of a plurality of elongatedbelts of flexible material, a plurality of crossbars extendingtransversely of said belts at spaced intervals and having portionsthereof embedded in said belts for interconnecting said belts, eachcrossbar having at least one exposed middle portion extending betweenopposing edges of said interconnected belts and a ferrule over eachmiddle portion adapted to engage driving means, the improvementcomprising:

said ferrule having integral upper, lower, forward and rearward wallswith said forward and rearward walls being flared at the longitudinalends thereof in the horizontal plane of said belts.

2. The improvement of claim 1 wherein said upper and lower walls havegenerally flat surfaces and are coplanar with the surfaces of saidbelts.

3. The improvement of claim 1 wherein said flexible material isinterposed between said flared ends of said ferrule and said middleportion of said crossbar.

4. The improvement of claim 1 wherein said forward and rearward wallsare arcuately shaped, the outer surfaces of all of said walls definingthe exterior periphery of said ferrule and the interior surfaces of allof said walls defining the interior periphery of said ferrule, at leastsaid interior surfaces of said forward and rearward walls being adaptedto closely embrace said middle portion of said crossbar.

5. The improvement of claim 1 wherein the inner surfaces of said forwardand rearward walls are flared at angles generally between l0to 30.

6. The improvement of claim 4 further including a longitudinallyextending slit through one of said upper and lower walls.

7. The improvement of claim 6 wherein said slit is generally V-shaped.

8. The improvement of claim 7 wherein said slit has a width of generallybetween 0.00 inches and 0.04 inches at said interior periphery,

9. The improvement of claim 8 wherein the inner surfaces of said forwardand rearward walls flare out wardly along a pair of arcuate pathsextending from a point on the longitudinal center of said forward andrearward walls to points at the uppermost and lowermost ends of saidforward and rearward walls at the longitudinal ends of said ferrule.

10. A new ferrule for use in an endless flexible belt comprised of aplurality of elongated belts of flexible material, a plurality ofcrossbars extending transversely of said belts at spaced intervals andhaving portions thereof embedded in said belts for interconnecting saidbelts, each said crossbar having at least one exposed middle portionextending between opposing edges of said interconnected belts, saidferrule being dimensioned to be received over one of said crossbarmiddle portions and comprising:

integral upper, lower, forward and rearward walls,

said forward and rearward walls being flared at the longitudinal endsthereof in the horizontal plane of said belts.

11. The ferrule as defined in claim 10 wherein said upper and lowerwalls have generally flat surfaces generally parallel to each other.

12. The ferrule as defined in claim 11 wherein said forward and rearwardwalls are arcuately shaped and disposed in a concave relationship toeach other.

13. The ferrule as defined in claim 12 further including alongitudinally extending slit through one of said upper and lower walls.

1. In an endless, flexible track comprised of a plurality of elongatedbelts of flexible material, a plurality of crossbars extendingtransversely of said belts at spaced intervals and having portionsthereof embedded in said belts for interconnecting said belts, eachcrossbar having at least one exposed middle portion extending betweenopposing edges of said interconnected belts and a ferrule over eachmiddle portion adapted to engage driving means, the improvementcomprising: said ferrule having integral upper, lower, forward andrearward walls with said forward and rearward walls being flared at theLongitudinal ends thereof in the horizontal plane of said belts.
 2. Theimprovement of claim 1 wherein said upper and lower walls have generallyflat surfaces and are coplanar with the surfaces of said belts.
 3. Theimprovement of claim 1 wherein said flexible material is interposedbetween said flared ends of said ferrule and said middle portion of saidcrossbar.
 4. The improvement of claim 1 wherein said forward andrearward walls are arcuately shaped, the outer surfaces of all of saidwalls defining the exterior periphery of said ferrule and the interiorsurfaces of all of said walls defining the interior periphery of saidferrule, at least said interior surfaces of said forward and rearwardwalls being adapted to closely embrace said middle portion of saidcrossbar.
 5. The improvement of claim 1 wherein the inner surfaces ofsaid forward and rearward walls are flared at angles generally between10*to 30*.
 6. The improvement of claim 4 further including alongitudinally extending slit through one of said upper and lower walls.7. The improvement of claim 6 wherein said slit is generally V-shaped.8. The improvement of claim 7 wherein said slit has a width of generallybetween 0.00 inches and 0.04 inches at said interior periphery,
 9. Theimprovement of claim 8 wherein the inner surfaces of said forward andrearward walls flare outwardly along a pair of arcuate paths extendingfrom a point on the longitudinal center of said forward and rearwardwalls to points at the uppermost and lowermost ends of said forward andrearward walls at the longitudinal ends of said ferrule.
 10. A newferrule for use in an endless flexible belt comprised of a plurality ofelongated belts of flexible material, a plurality of crossbars extendingtransversely of said belts at spaced intervals and having portionsthereof embedded in said belts for interconnecting said belts, each saidcrossbar having at least one exposed middle portion extending betweenopposing edges of said interconnected belts, said ferrule beingdimensioned to be received over one of said crossbar middle portions andcomprising: integral upper, lower, forward and rearward walls, saidforward and rearward walls being flared at the longitudinal ends thereofin the horizontal plane of said belts.
 11. The ferrule as defined inclaim 10 wherein said upper and lower walls have generally flat surfacesgenerally parallel to each other.
 12. The ferrule as defined in claim 11wherein said forward and rearward walls are arcuately shaped anddisposed in a concave relationship to each other.
 13. The ferrule asdefined in claim 12 further including a longitudinally extending slitthrough one of said upper and lower walls.